Stress is
a. positive or negative, depending on circumstances
b. a body's automatic physical response
c. a negative reaction to outside influences
d. a and b only

The human body automatically reacts to stress encountered in the outside world. Depending on how the person handles the stress, it can be a positive or negative effect. Stress is designed to enable the body to fight and operate under tough circumstances. In today's world, some people take on the burden of too much stress and it can end up being harmful to the body.

Air goes past the epiglottis and into the trachea when you breathe in. from there, it goes to your vocal cords in the larynx until it reaches the bronchi. from the bronchi, air passes into each lung.